Dredge pumps are indispensable equipment across various industries engaged in dredging operations. These pumps are specifically engineered to tackle the formidable task of removing sediment, sand, and debris from water bodies like rivers, lakes, and harbors. They play a pivotal role in maintaining navigational channels, reclaiming land, and extracting valuable resources. Known for their sturdy construction, high efficiency, and capability to handle abrasive and solid-laden fluids, dredge pumps can transport substantial volumes of materials over extensive distances, making them well-suited for demanding dredging projects. Available in diverse sizes and configurations, these pumps cater to a wide array of dredging requirements.
With years of practical experience, Tai’an Ocean Pump Co., Ltd. has not only conducted extensive research and refinement on the product itself but has also developed a comprehensive understanding of the supporting components such as power systems, control mechanisms, pipelines, and valves for dredge pumps. Additionally, OCEAN Pump has meticulously summarized guidelines for selecting and configuring pipelines and components for dredge pumps. The following provides a detailed explanation of this issue.
Selection and Configuration of Dredge Pump Pipeline
Sand Discharge Pipe Material Selection
The sand discharge pipes of large and medium-sized dredge pumps are generally selected from steel pipes or HDPE pipes.
Steel pipe: More steel pipes are used in the case of close distance or large pressure. The pressure of the steel pipe is large, no matter the external pressure or the internal pressure, it is larger than other plastic materials. Steel pipe can be cut and welded on site, it is easy to use. The recycling rate of steel pipe is high, even if the project is completed, steel pipe can still be sold at a good price, or be used for other purposes.
HDPE pipes are typically chosen for long-distance transportation due to their advantageous properties. With a smooth inner surface and a Manning coefficient of 0.009, HDPE pipes offer superior transport capacity compared to traditional pipes. Their smooth performance and non-adhesive nature not only enhance transport efficiency but also reduce pressure loss in pipelines and energy consumption during water delivery. Additionally, HDPE pipes made from new PE material exhibit excellent wear resistance.
In the realm of mud and sand transportation, HDPE pipes outperform steel pipes in terms of wear resistance, resulting in extended service life and improved cost-effectiveness. These pipes are highly resistant to aging and can withstand prolonged use. Featuring 2-2.5% uniformly distributed carbon black, HDPE pipes can endure outdoor storage and usage for up to 50 years without succumbing to damage from ultraviolet radiation. Moreover, their lightweight design facilitates easy transportation and assembly. Consequently, we typically recommend the utilization of HDPE sand discharge pipes for optimal performance and durability.
Steel Wire Lined Rubber Hose
For wholesale dredge pumps with specifications below 11kW, steel wire-lined rubber hoses are commonly used for drainage purposes. Consequently, these types of wholesale dredge pumps typically come equipped with hose connectors at the outlet. Workers only need to insert the hose connector into the hose and then secure them with a hoop or wire. If the customer opts for a steel pipe, it can be directly welded to the hose connector, or the hose connector can be removed and matched with a flange. However, if a hose is chosen, it’s essential to ensure that the hose meets the pressure requirements to prevent bursting. For high-pressure hoses, steel flanges are provided at both ends, and the flanges connected to them must adhere to the flange standards of high-pressure hoses.
Sand Suction Rubber Pipe
In practical applications, steel pipes and hoses are often used together as sand suction pipes. Steel pipes offer obvious advantages, but special attention must be given to the hoses. It’s crucial to use hoses lined with steel wire or steel rings to withstand negative pressure and prevent collapse when absorbing water. When configuring the sand suction rubber pipe, the pipe diameter should ideally be the same as or slightly larger than the sand discharge pipe diameter (but not excessively large). Moreover, for optimal on-site performance, the length of the water suction pipe should be kept as short as possible. Excessively long suction pipes can reduce efficiency and may cause cavitation in the wholesale dredge pump.
Soft Joint
Soft joints, also known as rubber tube soft joints, rubber joints, rubber soft joints, flexible joints, high-pressure rubber joints, and rubber shock absorbers, serve as vital components in piping systems. These hollow rubber products facilitate flexible connections between hard pipes, effectively reducing vibration and noise. Additionally, they can compensate for thermal expansion and contraction resulting from temperature changes, making them indispensable in various applications.
Soft joints play a crucial role in the disassembly and assembly of dredge pumps, providing flexibility and ease of installation. It’s essential to install soft joints at both the inlet and outlet of the dredge pump, especially on longer pipelines where they should be installed at intervals.
When selecting the diameter of the sand discharge pipe, sand suction pipe, and soft joint, it’s crucial to adhere to the design parameters of the dredge pump. We typically recommend matching diameters and advise against altering them arbitrarily. Furthermore, the pipeline’s pressure rating must be capable of withstanding the maximum pressure generated by the dredge pump to ensure safe and efficient operation.
Flange
Flange connection involves securing two pipes or pipe fittings onto a flange, then adding a flange gasket (typically rubber) and fastening them together with bolts between the two flanges to complete the connection. Some pipe fittings come equipped with their own flanges, which also utilize flanged connections. This method is vital in pipeline construction due to its ease of use and ability to withstand high pressure.
In the context of customized dredge pump pipelines, the pipeline flange typically consists of a flat plate welded steel flange. These flanges are suitable for connecting pipelines with a nominal pressure not exceeding 2.5MPa. It’s crucial to ensure that the selection of flanges aligns with national standards for pipelines to ensure compatibility and reliability.
Dredge Pump Valve Selection and Configuration
When using a dredge pump, the medium often contains impurities such as sand, mud, sediment, or slurry. Therefore, the valve configuration for such applications differs from that of clean water pumps.
Gate Valve
A gate valve operates with a gate plate as its opening and closing mechanism, moving perpendicular to the direction of fluid flow. Unlike other valves, gate valves can only be fully opened or fully closed and cannot be adjusted for throttling purposes. For the outlet valve of the sand pump, it’s essential to use a gate valve rather than a ball valve or butterfly valve. The recommended gate valve model is the Z44W type, with the following representation method:
Z: Valve form – Gate valve
4: Connection form – Flange connection
4: Gate valve structure form – Parallel double gate (flat gate valve). Other gate valve structures, such as Z41W, are also available.
W: Sealing surface or lining material – The seat sealing surface material is directly processed by the valve body. Alternatively, stainless steel material (e.g., Z41H) can be selected.
1.6: Nominal pressure of gate valve – 1.6MPa (The number cast on the gate valve is 16). Different nominal pressure gate valves should be selected based on the maximum lift of the sand pump. For instance, Z44W-2.5DN150.
DN100: Nominal size of gate valve – DN100 (4 inches). Different nominal sizes of gate valves should be chosen according to the flow requirements of the sand pump. For example, Z44W-2.5DN200.
Check Valve
In the design of the dredge pump pipeline system, incorporating a check valve is essential. Its primary function is to prevent the backflow of sediment in the pipeline, which could lead to pump overload and blockage. It is recommended to use a swing check valve, although a lift check valve can also be considered. However, slow closing check valves should be avoided.
Note: Lift check valves come in two types: horizontal and vertical. It’s important not to confuse them during the design phase. The recommended check valve model is the H44W type, represented as follows:
H: Valve form – Check valve
4: Connection form – Flange connection
4: Connection form – Flange connection. Alternatively, 1. lift type (H41 for horizontal lift check valve), 2. vertical type (H42 for vertical check valve) can be chosen.
W: Sealing surface or lining material – The seat sealing surface material is directly processed by the valve body. Stainless steel material (e.g., H41H) can also be chosen.
1.6: Nominal pressure of the check valve – 1.6MPa (The number cast on the valve is 16). Different nominal pressure check valves should be selected based on the maximum lift of the sand pump, e.g., H44W—2.5DN150.
DN100: Nominal size of the check valve – DN100 (4 inches). Different nominal sizes of check valves should be chosen according to the flow requirements of the sand pump, e.g., H44W-2.5DN200.
Pressure Gauge and Gauge Valve
The pressure gauge serves as the foundation for assessing the various operational conditions of the dredge pump.
Judgment of forward and reverse rotation: After closing the gate valve, observe the pressure gauge. A higher reading indicates forward rotation, while a lower reading suggests reverse rotation. This method is the most effective and accurate for determining rotation direction, as other methods may have limitations and errors.
After the dredge pump operates normally, check the pressure gauge value to calculate pipeline loss, assess remaining head, and verify pump selection and efficiency. A 10% increase in efficiency could result in significant energy savings, such as 170,000 kWh annually for a 200 kW pump.
During operation, a sudden increase in pressure suggests a blocked sand discharge pipe, while a sudden drop indicates blockages at the suction port or filter, necessitating prompt cleaning. Sharp drops accompanied by fluctuations signal air intake by the pump, requiring checks on water levels or the suction pipe.
Significant pressure drops after closing the gate valve over time may indicate excessive pump wear, necessitating replacement of worn parts.
Therefore, large and medium-sized dredge pumps should be equipped with a pressure gauge when designing drainage pipelines. Diaphragm-type pressure gauges are recommended, with radial direct connections. The gauge range should cover 1/3 to 2/3 of the maximum pump lift. Due to the abrasive nature of the pumped medium, additional pressure gauges should be prepared, preferably equipped with stainless steel gauge valves. An exhaust valve between the gauge valve and pressure gauge can discharge mud and water, extending the gauge’s life.
During design, weld a pipe joint to the steel pipe at the pump’s water outlet, and install the gauge valve and pressure gauge. It’s advisable to install a pressure gauge in the sand suction pipe.
Release Valve
Add air release valves at pipeline bulges and high points to release trapped air during pump startup. After startup, close the valve. Failure to do so may trap air, affecting pump performance and lifespan.
Additionally, include a sand discharge pipe at the pipeline’s low point. After pump shutdown, open the sand discharge pipe’s gate valve to release sediment and prevent pipe blockage. In cold weather, discharge the mud and water mixture to prevent freezing and pipeline damage. If the discharge pipe lacks an elevated high point, the air release valve may be omitted.
When designing the sand pump’s pipeline, it’s essential to connect the suction pipe to the bottom. During design and installation, ensure the air release valve is positioned at the highest point of the suction port on the pump. The suction pipe should run straight down. This configuration allows for the release of air from both the suction pipe and the pump cavity, ensuring the successful operation of the irrigation pump. Proper air release is crucial for filling the pump; without it, the water pump may fail to start.
Bottom Valve Filter and Non-bottom Valve Filter
When designing and using a sand suction pipe, it’s important to decide whether to use a bottom valve filter with the dredge pump or not. The purpose of the suction filter for the dredge pump is as follows:
1. Blocking large solid particles: When designing and manufacturing the suction filter, customers need to consider the maximum particle size that the dredge pump can handle. This ensures that the filter prevents debris larger than the allowed size from entering the pump cavity. If large particles get inside, it can cause problems like the impeller getting stuck or the motor burning out. The bottom valve of the dredge pump should have a swing type structure specifically designed for this purpose, instead of using a common bottom valve meant for clean water pumps.
2. Increasing sediment concentration: The suction chamber, which includes the filter and other components, helps maintain a consistent slurry of sediment during dredge pump operation. Sediment enters the suction cavity through the filter holes, creating a uniform slurry. This prevents the impeller suction port from getting blocked by sediment. The filter screen of the dredge pump is larger than that of clean water pumps or sewage pumps. The size of the filter screen area depends on the mud concentration. For mining sand or pumping high-concentration mud, customers can purchase a hydraulic agitator designed for this purpose.
3. Preventing debris from entering: The sand dredging pump cannot handle debris and is not a non-blockage pump. If the water contains a significant amount of debris like leaves, plastic bags, or weeds, it’s crucial to include a blocking device during the design stage. Customers can consult OCEAN Pump technical engineers to select the appropriate suction filter device when purchasing sand pump machines.
Conclusion
When choosing pipelines, the decision between steel pipes and HDPE pipes depends on factors like distance, pressure, and wear resistance requirements. HDPE pipes are often preferred due to their smooth surface, high transport capacity, and excellent wear resistance. Soft joints in HDPE pipes allow flexible connections, reducing vibration, noise, and accommodating thermal expansion and contraction.
Valve selection is crucial to handle impurities in the pumped medium. Gate valves are recommended for sand pump outlets, while swing check valves prevent backflow and pump overload. Pressure gauges and gauge valves provide valuable information for monitoring pump performance, determining pipeline losses, and optimizing energy efficiency.
Tai’an Ocean Pump Co., Ltd. is a leading enterprise specializing in the design, production, and sale of sand pumps and sand dredgers. They prioritize core technological innovation and product quality to meet customers’ needs effectively. By continuously improving their service system and implementing international brand strategies, customer satisfaction is their ultimate goal. OCEAN Pump is committed to providing reliable solutions for demanding dredging projects.
